Denitration of waste acid mixtures



Patented Apr. 22, 19,30 Y

*UN'TE' *WILLI BscHINdor HALLE-saam, campani nnivrrna'rron 6r WASTE AcrDJn-rrxrunns Application led August 15,-1927, Serial No; 213,025, and inweriiiany A'September 3, 1926.

The processes hitherto known for fdenisulphuric acid which runs ofi' `continually trating'waste mixed acids consist in introduceither directly 'into the cooler K or the vapors ing the waste acid mixture into the upper are condensed'in the column .B and will be portion of a column which is provided wlth drawn olf-:by meansof pi e c. It will be'evia filling material, bell bottoms or other indent from the drawing t at vaporslpass u 5c. sertions, and superheated steam or superwardly throughthe appa-rahis byway of'tiiie heated air into the lower portion of the col- )connecting tu es irq-6 and p and liquid duwn-` umn in countercurrent vto the iiow of acid, wardly by way of the smaller tubes e and c. thereby .effecting a separation of the compo- The nitric acid vapors escaping from col-' 10 nents contained in the waste acid so that, umn B are washed 1n column D with s ioo for instance, by the process according to Gerphuric acid and dried so that the nitric acid man Patent No. 182,126 or British Patent No. vapors are recovered in likewise highly. con- 17 ,316 015,1902, sulphuric acid of 65% to 70% centrated form in the cooler E while the reconcentration is obtained in the lower'fpor- 'maining nitrose va ors pass into absorption l tion ofthe column, while from the upper portowers (not shown?. 'in a closed operating .o5 'tion thereof nitric acid vapor mixed with cycle'tlierefore' all components are obtained in nitric'oxide has to be introduced into a cone` ltheir original form,"that is to say as densa-tion plant for the further ,conversiony 1. Strong sulphuric'acid l to nitric acid. The dilute sulphuric acid leavv 2. Pure water vapor p 20 ing the denitration drum has then to be lib- Strong nitric acid.` to erated fromwater by known processes in a .fin a separate preliminary heater` F the separate high concentration apparatus so that waste .acid to be denitrated, for example, the denitration is onnected with cqn'sidernitrolycerinelw'aste acid, is preliminarily --'able costs from the eat-supply point of view. heate so that the organic constituents con- According to this invention it has been tained in the waste acid are previously decom- .F5 found that denitration of waste acid can be posed so that explosions arising often in combined with considerable advantages, with the den itratingcolumn are avoided. Vapore the high concentration of sulphuric acid progiven 0H during this treatment are appropri'E vided a portion of the vapors containing sulately removed into the absorption apparatus. l

phuric acid and obtained during the high The present process also aders the advan eo concentration isv utilized to eect the denitage that .the apparatus ma be employed g tration, the fremaining portion of vapors bewithoutalteration for the high concentration ing subjected to dephlegmation in order to of nitric acid of sulphuric acid when the a e get rid of the water entering with the waste paratus is not required for waste sulphuric mixed acids in the form of steam. nitric acid. The process ensures continuous c5;

A plant for carrying the process into eect Yuse of theV apparatus' avoiding interruptions isV illustrated dia-grammatically in the anof working which, as is known, arez'injurious..

- nexed drawing. v Moreover with the aid of the sance a patatus Referring'to the drawing B represents the diluted nitric acid can be, subjectedp to high 40 denitration column, and C the high conc`nconcentration according to the process .as set e@ tration boiler for the sulphuric acid. The forth in German Patent No. 398,320. For the sulphuric acid vapors escapingdrom C enter concentration of nitric acid dilute nitric acid int-o the column A. A portion of these vapors is sup lied to thefcolum'n B by the'pipel passes by way of pipepb into-thecolumn B vwhile y means o Va' tubem sulphuric.acid

,and denitrates in known manner the waste of 96-98% concentration is also'll'ed in so that 95 acid introduced from 'container F into colnitricacid is con centratedinknown man# umn B. The remainder of the vapors rising ner. The column D serves merely ,then for in column A is dephlegmated so that steam the dryin of 'the nitric acid vapor.` By only escapes from the top of the column A. meansof t e tube gstron; sulphuric acid is The boiler C contains-highly concentrated introduced for washing te hot nitric acid. to@

. and vapors which are` thenconducted to the l 'l'.j A.Ay continuous Wast acid COmPl'SIIg the Stops of conceny. f what 1 lamas z `condenser E, the nitrictcidin vapor form thus being as free as possible from water. The high concentration of the sulphuric acid takes place in the column A, the;di1ute'su1 'phuric acid tobe concentrated is' led in by Way'of the tbem/andovvs in concentrated form from th-chamber C into the YcoolenV K.

tube A.`

A.The Water vapor-escapes by JWay. of the process for denitrating ta/,ting -sulphuri'c acid, leading 'art of 'the sulphu'rlc acid vapors into a denltration column in counter-current. to a `110W, of heated waste acid, dephlegmating the remainder of' y thesulphuric acid by removing the Water-- steam from the nitric acid, washing the nitric acid vapors with sulphuric acid, condensing the nitric acid vapors to concentrated nitric acid and returning the washing sulphuric .acidi to the' first concentration stage.

ing column in counter current to a iiow of. y. heated Waste. acid, dephlegmating the remainder of the vapors containing sulphuric 2. yA continuous process for denitrating waste sulphuric-nitric acid comprising the stepsof highly concentrating sulphuric acid in a column, leading part of the vapors containing sulphuric -acid into'a second denitratacid by removing the water vapor from the Waste acid, Washing the nitric acid vapors NWith fsulphuric acid in a third column, con- `3x51 "nitricf acid and retlrning the washing sullphuric acid to the sulphuric acid concentratdensing the nitric acid vapors to concentrated ing boiler. 4 f U n testimony whereof l have axed my lsignature. l

WHALI BSCHING. 

